Integrated circuit packaging technology has seen an increase in the number of integrated circuits mounted on a single circuit board or substrate. The new packaging designs are more compact in form factors, such as the physical size and shape of an integrated circuit, and providing a significant increase in overall integrated circuit density. However, integrated circuit density continues to be limited by the “real estate” available for mounting individual integrated circuits on a substrate. Even larger form factor systems, such as personal computers, compute servers, and storage servers, need more integrated circuits in the same or smaller “real estate”. Particularly acute, the needs for portable personal electronics, such as cell phones, digital cameras, music players, personal digital assistants, and location-based devices, have further driven the need for integrated circuit density.
This increased integrated circuit density, has led to the development of multi-chip packages in which more than one integrated circuit can be packaged. Each package provides mechanical support for the individual integrated circuits and one or more layers of interconnect lines that enable the integrated circuits to be connected electrically to surrounding circuitry. Current multi-chip packages, also commonly referred to as multi-chip modules, typically consist of a printed circuit board substrate onto which a set of separate integrated circuit components are attached. Such multi-chip packages have been found to increase integrated circuit density and miniaturization, improve signal propagation speed, reduce overall integrated circuit size and weight, improve performance, and lower costs—all primary goals of the computer industry.
Multi-chip packages whether vertically or horizontally arranged, can also present problems because they usually must be pre-assembled before the integrated circuit and integrated circuit connections can be tested. Thus, when integrated circuits are mounted and connected in a multi-chip module, the individual integrated circuits and connections cannot be tested individually, and it is not possible to identify known-good-die (“KGD”) before being assembled into larger circuits. Consequently, conventional multi-chip packages lead to assembly process yield problems. This fabrication process, which does not identify KGD, is therefore less reliable and more prone to assembly defects.
Moreover, vertically stacked integrated circuits in typical multi-chip packages can present problems beyond those of horizontally arranged integrated circuit packages, further complicating the manufacturing process. It is more difficult to test and thus determine the actual failure mode of the individual integrated circuits. The substrate and integrated circuit are often damaged during assembly or testing, complicating the manufacturing process and increasing costs. The vertically stacked integrated circuit problems can be greater than the benefits.
In addition, multi-chip packages generally provide higher density of integrated circuits but present yet other challenges. Additional structures, such as printed circuit boards, interposers, or flexible wiring, must be currently used to connect the integrated circuits in the multi-chip package. Current embedded die packages create vias inside the package using processes such as etching, laser drilling, via plating, filling, etc. These processes are expensive and involved more process steps. This, in turn, increases the manufacturing cost of making such packages.
These additional structures add cost, manufacturing complexity, potential failure areas, and potential reliability problems. A primary concern is the warping of package components that can cause manufacturing failures due to faulty connections. The warping can also cause finished packages to not meet coplanarity specifications required for reliable assembly at the next system level. In many cases the warped packages can not be reworked or repaired, which adds scrap expense to the manufacturing process.
Thus, a need still remains for an integrated circuit packaging system that can improve the yield of stacked packages by maintaining the planarity of the bottom package. In view of the demand for increased integrated circuit density in shrinking spaces, it is increasingly critical that answers be found to these problems. In view of the ever-increasing commercial competitive pressures, along with growing consumer expectations and the diminishing opportunities for meaningful product differentiation in the marketplace, it is critical that answers be found for these problems. Additionally, the need to reduce costs, improve efficiencies and performance, and meet competitive pressures adds an even greater urgency to the critical necessity for finding answers to these problems.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.